Acta Pharm. 70 (2020) 239–247 Short communication https://doi.org/10.2478/acph-2020-0005 Effects of new generation triptans – frovatriptan and almotriptan – on hemodynamic parameters in intact male and female rats KREMENA SARACHEVA1 The introduction of the second generation triptans in 2 PETAR HRISCHEV clinical and experimental practice was a major progress LILI YA VASILEVA 1 MARIYAN TOPOLOV1 in the pharmacotherapy of migraine. Frovatriptan is a 2 JULIA NIKOLOVA second generation triptan with strong 5-HT1B/1D seroto- DAMIANKA GETOVA3 nergic agonism and low 5-HT1A/7 receptor affinity, while 1 Department of Pharmacology and Drug almotriptan possesses not only the typical 5-HT1B/1D re- Toxicology, Faculty of Pharmacy, Medical ceptor agonist activity, but shows an affinity to the 5-HT1F University Plovdiv, Plovdiv, Bulgaria receptor. The aim of our study was to assess the impact of frovatriptan and almotriptan on hemodynamics in male 2 Department of Physiology, Faculty of and female rats. We used a non-invasive “tail-cuff” method Medicine, Medical University Plovdiv to measure the arterial blood pressure. Female and male Plovdiv, Bulgaria Wistar rats were treated separately with high and low dosages of frovatriptan and almotriptan. Male and female 3 Laboratory of Neuropharmacology rats showed reduction in all hemodynamic parameters, Technological Center of Emergency but only male rats showed an increase in the heart rate. In Medicine (TCEMED), Plovdiv, Bulgaria general, we could say that both almotriptan and frovat- riptan potentiate cardiovascular safety. Acccepted May 13, 2019 Published online May 30, 2019 Keywords: almotriptan, frovatriptan, rat, arterial pressure Despite the fact that triptans were designed to exert relatively similar antimigraine activity and side-effects profile, there are some studies that show some controversies in their cardiovascular safety and sustainability. Several studies have shown that hyperten- sion is often associated with migraine and can even lead to its chronic development. Hypertension is thought to aggravate vascular endothelial dysfunction, which negatively affects the incidence and severity of migraine attacks (1). The control of arterial pressure is closely related to the specificities of blood supply in some vascular areas. Neuronal brain activity is a major factor that could influence blood flow (2). Serotonin (5-HT) could influence some heart functions by its receptors, the effects of which are very complex in essence. For example, 5-HT can act as a sympatholytic by activa- tion of the 5-HT1 receptors on sympathetic nerve terminals that inhibit the norepinephrine (NE) release. This mechanism contributes to a reduced cardiac output, which is associated with a decrease in blood pressure. On the other side, 5-HT could have some stimulating effects on the heart (3). The 5-HT receptor mechanisms in the heart are species-dependent. * Correspondence; e-mail: [email protected] 239 K. Saracheva et al.: Effects of new generation triptans – frovatriptan and almotriptan – on hemodynamic parameters in intact male and female rats, Acta Pharm. 70 (2020) 239–247. For example, the activation of 5-HT2A receptors in rats, 5-HT4 receptors in pigs and hu- mans, and 5-HT7 receptors in cats leads to an increase of the heart rate. The authors assume that 5-HT could both increase and decrease blood pressure by its activity in the heart (4). The frequency of triptan-related cardiovascular side-effects in clinical trials and in practice has been extremely low. When present, they usually affect patients with cardio- vascular risk or cardiovascular disease. Few cases of cardiovascular side-effects were ob- served among patients that do not suffer from any cardiovascular pathology. Side-effects include peripheral vasoconstriction and rise in blood pressure in the case of uncontrolled hypertension. Because of this, there is a need for careful triptan prescribing to patients at risk (5). Nowadays, there are no specific scales that could assess the efficacy of triptan treat- ment during a migraine attack in patients suffering from hypertension. Tullo et al. (6) made a retrospective analysis of three randomized, double-blind, cross- over studies involving hypertensive and normotensive men and women aged 18–65 years suffering from migraine, with or without aura. The patients were treated with frovatriptan and other triptan agents (zolmitriptan, rizatriptan and almotriptan). Recurrent headaches have been more frequent among hypertonic patients than in normotensive patients treated with other triptans except frovatriptan, which is not surprising, having in mind the long half-life of the drug (~26 h). A conclusion that could be drawn from this is that hyperten- sive patients are less susceptible to triptan treatment. In the following research, we will make a comparative analysis of efficacy after one single application of frovatriptan and almotriptan on blood pressure and heart rate in male and female rats. We use single applications of these drugs because they are used only in the treatment of acute exacerbations and not as basic antimigraine therapy. EXPERIMENTAL Chemicals Saline 0.9 % NaCl was used in control groups. Frovatriptan succinate monohydrate (frova) (≥ 98 %) and almotriptan malate (almo) (≥ 98 %) were obtained from Sigma-Aldrich Chemie GmbH (Germany). Animals Animals used in the experiments were male and female albino Wistar rats with an approximate body mass of 180–220 g. The total number of animals used in the experiments is 32 (16 males, 16 females), each group consisting of 8 animals. Female animals were of reproductive age, not ovariectomized and not estrogen-treated. All experimental rats were housed on a 12-hour light/dark cycle under controlled temperature and lighting condi- tions, while food and water were provided ad libitum. Exclusion criteria: underweight rats, diseased animals, not-matured enough animals, and animals that had been previously treated with other than the before-mentioned substances. We have not registered any incidents during the experiments. Experimental design There were two series of experiments carried out on rats, based on sex: in the 1st series we had used female rats and in the 2nd series we had used male rats. For each experiment 240 K. Saracheva et al.: Effects of new generation triptans – frovatriptan and almotriptan – on hemodynamic parameters in intact male and female rats, Acta Pharm. 70 (2020) 239–247. in the 1st and in the 2nd series, there was one control group treated subcutaneously (s.c.) with saline 0.9 % NaCl only (0.1 mL per 100 g b.m.) and four test groups treated subcutane- ously (s.c.) as it follows: the 1st group was injected with frovatriptan 2.5 mg kg–1 b.m.; the 2nd group was injected with frovatriptan 5 mg kg–1 b.m.; the 3rd group was injected with almotriptan 3 mg kg–1 b.m.; the 4th group was injected with almotriptan 6 mg kg–1 b.m. Forty minutes after the drugs had been injected, animals were tested according to the in- dicated method. All test groups in the respective series were compared to the control group (injected with saline only). The total number of animals used in the experiment was 80: 40 males and 40 females; 8 animals in each group. Method The arterial blood pressure was examined non-invasively using the so-called “tail- -cuff” method. All the experiments were carried out by the hemodynamic apparatus NIBP 200A (Biopac Systems Inc., USA) and its respective software package МР150. The animals were not anesthetized. All rats were initially warmed in a thermostat (Binder, Germany) up to 37 ° С. Afterwards, the animals were put into a restrainer in order to measure the arterial blood pressure using a cuff on the base of their tails. Before each measurement of the blood pressure, the rats were put into the restrainer for 5 min in order to get used to the stress levels. The values of systolic blood pressure (SBP) and diastolic blood pressure (DBP) were calculated as the means of 3 independent measurements. Their derivatives – pulse pressure (PP) and mean arterial pressure (MAP) – were calculated as follows: PP = SBP – DBP and MAP = DBP + (PP/3). All the experimental protocols in this study were approved by the Ethical Committee of the Bulgarian Food Safety Agency with № 97/22.05.14 and were carried out following the guidelines of the European Directive 2010/63/EU. Statistical processing The statistical software SPSS version 19.0 was used for the multi-variant analysis. The mean and standard error of the mean (± SEM) were calculated for each group. A non- parametric Shapiro-Wilk test was performed to determine the level of distribution. F-test for variances and independent sample t-test, assuming equal or unequal variances, were used to compare the experimental groups with the corresponding control group. A p < 0.05 was considered as representing a statistically significant difference. RESULTS AND DISCUSSION Cardiovascular effects of frovatriptan and almotriptan in female rats In the first series of experiments, the female group of rats treated with frovatriptan of 2.5 mg kg–1 did not exhibit any significant change in hemodynamic parameters. The only group of animals, that significantly reduced DBP and MAP compared to the control group with saline, were those injected with the higher dosage of frovatriptan 5 mg kg–1 (Fig. 1). 241 K. Saracheva et al.: Effects of new generation triptans – frovatriptan and almotriptan – on hemodynamic parameters in intact male and female rats, Acta Pharm. 70 (2020) 239–247. Fig. 1. Cardiovascular effects of frovatriptan after single administration in female rats (mean ± SEM, n = 8). A significant difference compared to the control group:p * < 0.05; DBP – diastolic blood pres- sure, PP – pulse pressure, MAP – mean arterial pressure, SBP – systolic blood pressure. Fig. 2. Cardiovascular effects of almotriptan after single administration in female rats (mean ± SEM, n = 8). A significant difference compared to the control group:p * < 0.05; DBP – diastolic blood pres- sure, PP – pulse pressure, MAP – mean arterial pressure, SBP – systolic blood pressure.